Of course it does, but it would be naive to assume that without hard work and stretching one's compositional knowledge that this would occur. If you are in a rut right now, buy a Harmony (so called "Music Theory" now) textbook like Piston's "Harmony" and study that for awhile. Your mind will be busting with so many new ideas that you will get right back to writing, and your compositions will be much richer. Assuming you have already done this, try some score-reading and harmonic analysis of 'adventurous' compositions like some of Ravel's piano works.

You can also improve the songs you have "finished". Find the parts you are not happy with and make them sound better. What could make them sound better? Maybe analyze the parts and find out what you don't like about them? Are they too cliche? What makes them too cliche? How could you change it not to sound too cliche? Remember that you can also use just one idea of your old song and write a completely new song based on that idea.

Do your songs have all instruments or is it just guitar? Adding other instruments makes it sound a lot better. You can also improve your song by adding cool drum beat or bassline. The "background" instruments can make a simple riff sound freaking cool.

You can also improve the songs you have "finished". Find the parts you are not happy with and make them sound better. What could make them sound better? Maybe analyze the parts and find out what you don't like about them? Are they too cliche? What makes them too cliche? How could you change it not to sound too cliche? Remember that you can also use just one idea of your old song and write a completely new song based on that idea.

I've done all of this at times. Songs I started several years ago I'm still improving. Now, granted, you don't want to never finish a song. (In my case, I'm finishing songs for my EP that I'll record in the summer.) However, you can improve songs that you are unsatisfied with.

Quote:

Do your songs have all instruments or is it just guitar? Adding other instruments makes it sound a lot better. You can also improve your song by adding cool drum beat or bassline. The "background" instruments can make a simple riff sound freaking cool.

This is also an excellent idea. Some the best songs feature more than one instrument. (The obvious example of this is classical symphonies, but there are many rock bands that use the idea of writing for more than one instrument.) Remember that, if you write for the whole set of instruments, it will be a much fuller song.

Experiment with writing parts for piano (assuming you have a keyboard). Write out some bass parts as well.

All of this said, you won't ever get anywhere if you never have the musical knowledge to improve your songs. You need to acquire the knowledge you need (theory) and apply that to your songs.

The best way to improve your songwriting is to continually learn songs that fits the genre, easy or hard no matter just learn a crap-load of songs. (doesn't have to be similar songs, but for practicality's sake)

Eventually you'll come across stuff you're not used to nor would you think of when songwriting, and if persistent enough you'll figure out how that works why it works and you should be able to implement your new view from outside the window to your own music, i would say think outside the box but don't let that expression confuse you.